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/* $Id$ */
/*
* Copyright (C) 2003-2006 Benny Prijono <benny@prijono.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifndef __PJMEDIA_SILENCE_DET_H__
#define __PJMEDIA_SILENCE_DET_H__
/**
* @file silencedet.h
* @brief Adaptive silence detector.
*/
#include <pjmedia/types.h>
PJ_BEGIN_DECL
/**
* Opaque declaration for silence detector.
*/
typedef struct pjmedia_silence_det pjmedia_silence_det;
/**
* Create voice activity detector with default settings. The default settings
* are to perform adaptive silence detection, which adjusts the noise level
* dynamically based on current input level.
*
* @param pool Pool for allocating the structure.
* @param p_sd Pointer to receive the silence detector instance.
*
* @return PJ_SUCCESS on success.
*/
PJ_DECL(pj_status_t) pjmedia_silence_det_create( pj_pool_t *pool,
pjmedia_silence_det **p_sd );
/**
* Set the sd to operate in adaptive mode.
*
* @param sd The silence detector
* @param frame_size Number of samples per frame.
*
* @return PJ_SUCCESS on success.
*/
PJ_DECL(pj_status_t) pjmedia_silence_det_set_adaptive( pjmedia_silence_det *sd,
unsigned frame_size);
/**
* Set the sd to operate in fixed threshold mode.
*
* @param sd The silence detector
* @param frame_size Number of samplse per frame.
* @param threshold The silence threshold.
*
* @return PJ_SUCCESS on success.
*/
PJ_DECL(pj_status_t) pjmedia_silence_det_set_fixed( pjmedia_silence_det *sd,
unsigned frame_size,
unsigned threshold );
/**
* Disable the silence detector.
*
* @param sd The silence detector
*
* @return PJ_SUCCESS on success.
*/
PJ_DECL(pj_status_t) pjmedia_silence_det_disable( pjmedia_silence_det *sd );
/**
* Perform voice activity detection on the given input samples. This
* function uses #pjmedia_calc_avg_signal() and #pjmedia_silence_det_apply()
* for its calculation.
*
* @param sd The silence detector instance.
* @param samples Pointer to 16-bit PCM input samples.
* @param count Number of samples in the input.
* @param p_level Optional pointer to receive average signal level
* of the input samples.
*
* @return PJ_SUCCESS on success.
*/
PJ_DECL(pj_bool_t) pjmedia_silence_det_detect( pjmedia_silence_det *sd,
const pj_int16_t samples[],
pj_size_t count,
pj_int32_t *p_level);
/**
* Calculate average signal level for the given samples.
*
* @param samples Pointer to 16-bit PCM samples.
* @param count Number of samples in the input.
*
* @return The average signal level, which simply is total level
* divided by number of samples.
*/
PJ_DECL(pj_int32_t) pjmedia_calc_avg_signal( const pj_int16_t samples[],
pj_size_t count );
/**
* Perform voice activity detection, given the specified average signal
* level.
*
* @param sd The silence detector instance.
* @param level Signal level.
*
* @return PJ_SUCCESS on success.
*/
PJ_DECL(pj_bool_t) pjmedia_silence_det_apply( pjmedia_silence_det *sd,
pj_uint32_t level);
/**
* Declaration linear2ulaw
*/
unsigned char linear2ulaw(int pcm_val);
PJ_END_DECL
#endif /* __PJMEDIA_SILENCE_DET_H__ */
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